1. Field of the Invention
The present invention relates to a heating resistor for ceramic heaters, ceramic heaters and a method of manufacturing ceramic heaters, and particularly to a heating resistor for ceramic heaters used for heating glow plugs of a diesel engine or others, ceramic heaters employing the same, and a method of manufacturing the ceramic heaters.
2. Description of the Related Art
There have conventionally been known instruments which employ heating resistors for ceramic heaters provided with various kinds of rising temperature properties (e.g., resistance temperature coefficient) used at high temperatures of 1000.degree. C. or more such as glow plugs, including metals of W, Mo, Ti, Zr and Hf, or their carbides, nitrides and suicides.
However, recently in response to applications, rapidly heightening temperature properties or heating properties at constant temperatures are required, and many applications do not meet the heightening temperature requirements. Since heightening temperature properties are decided by the heating resistor, it was very often difficult to manufacture ceramic heaters having optional heightening temperature properties. In addition, these resistant materials were, when baking, insufficient in sintering, and caused exceptional grain growth and thereby decreased strength.